lseek64 - phpMan

LSEEK64(3)                 Linux Programmer's Manual                LSEEK64(3)



NAME
       lseek64 - reposition 64-bit read/write file offset

SYNOPSIS
       #define _LARGEFILE64_SOURCE
       #include <sys/types.h>
       #include <unistd.h>

       off64_t lseek64(int fd, off64_t offset, int whence);

DESCRIPTION
       The  lseek(2) family of functions reposition the offset of the open file associated
       with the file descriptor fd to offset bytes relative to the  start,  current  posi-
       tion,  or  end  of  the  file,  when  whence  has  the value SEEK_SET, SEEK_CUR, or
       SEEK_END, respectively.

       For more details, return value, and errors, see lseek(2).

       Four interfaces are available: lseek(), lseek64(), llseek(),  and  the  raw  system
       call _llseek().

   lseek
       Prototype:

            off_t lseek(int fd, off_t offset, int whence);

       The  library  routine lseek() uses the type off_t.  This is a 32-bit signed type on
       32-bit architectures, unless one compiles with

            #define _FILE_OFFSET_BITS 64

       in which case it is a 64-bit signed type.


   lseek64
       Prototype:

            off64_t lseek64(int fd, off64_t offset, int whence);

       The library routine lseek64() uses a 64-bit type even when off_t is a 32-bit  type.
       Its prototype (and the type off64_t) is available only when one compiles with

            #define _LARGEFILE64_SOURCE

       The  function lseek64() is available since glibc 2.1, and is defined to be an alias
       for llseek().


   llseek
       Prototype:

            loff_t llseek(int fd, loff_t offset, int whence);

       The type loff_t is a 64-bit signed type.  The library routine llseek() is available
       in  libc5  and glibc and works without special defines.  Its prototype was given in
       <unistd.h> with libc5, but glibc does not provide a prototype.  This is bad,  since
       a  prototype  is needed. Users should add the above prototype, or something equiva-
       lent, to their own source.  When users complained about data loss caused by a  mis-
       compilation of e2fsck(8), glibc 2.1.3 added the link-time warning

            "the `llseek? function may be dangerous; use `lseek64? instead."

       This makes this function unusable if one desires a warning-free compilation.


   _llseek
       All  the  above functions are implemented in terms of this system call.  The proto-
       type is:

            int _llseek (int fd, off_t offset_hi, off_t offset_lo,
            loff_t *result, int whence);

       For more details, see llseek(2).

SEE ALSO
       llseek(2), lseek(2)



Linux                             2004-12-11                        LSEEK64(3)

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